Conventionally, decoloring apparatus decolors an image that has been printed on a sheet with a decolorable color material, in order to reuse the sheet. In such a decoloring apparatus, the sheet on which an image is printed with the decolorable color material is conveyed by a sheet conveying unit to a decoloring unit to decolor the image. The sheet conveying unit includes a scanner for scanning the image on the sheet conveyed to the decoloring unit.
The quality of the image scanned by the scanner is lowered if the conveyance speed of the sheet is unstable. If the distance between the scanner and the decoloring unit is shorter than the length of the sheet in the conveyance direction, different portions of the sheet pass through the scanner and the decoloring unit at the same time. If the sheet is affected by the sheet feeding resistance when entering the decoloring unit or when passing through the decoloring unit, the conveyance speed of the sheet passing through the scanner becomes unstable. The conveyance speed of the sheet should be maintained with high precision in order to carry out high resolution image scanning.
However, it is not practical to maintain the conveyance speed of the sheet with high precision even when the front end of the sheet enters or passes through the decoloring unit.